This invention relates generally to transmissions, and in particular to a sliding gear, fully synchronized, multi-speed and reverse transmission including an improved cluster gear assembly defining a one-piece, live countershaft with three bearing journals. In particular, the invention relates to an improved method of assembling such a transmission.
In lower power-to-weight vehicles, multispeed manual transmissions generally are employed to provide the range of output torques needed for efficient vehicle operation. Some such transmissions provide the various speed ratios by selectively engaging separate gearsets, and include as a portion thereof a cluster gear assembly having a fixed countershaft. However, experience has shown that the use of a live countershaft provides increased gear rigidity, and increased gear and bearing life, especially where needle bearings are used. The use of needle bearings requires attention to the effect of deflection on thrust surfaces.
Kebel et al U.S. Pat. No. 3,916,712 issued Nov. 4, 1975 discloses a transmission incorporating a cluster gear having a live, two-piece countershaft journalled in three needle bearings. The two-piece countershaft compensates for any bearing misalignment. That patent is copending and of common assignee herewith, and is incorporated herein by reference. There remains a need to provide a cluster gear incorporating a live, one-piece countershaft journalled in three bearings in such a manner as to eliminate preloads on the bearings, thereby improving the load carrying capacity of the transmission.